A GAS FILTER ELEMENT

Abstract: First and second substantially identic layers (15) of rigid material each comprise a plurality of zones, each zone being defined by parallel fold lines (1, 2). The layers are formed of wall elements (10) extending between fold line (2) and a fold line (3), and of wall elements (11) extending between fold line (3) and fold line (1), each wall element (11) containing a plurality of openings (4) spaced along the direction of said fold lines. To form the filter element the two layers (15) are joined together along each fold line (2) to the opposite fold line (1), thus providing a series of chambers (5). The unpurified air flow enters these chambers through the openings (4) of a first layer (15) and exits substantially purified through the openings (4) of the second layer (15).

Description: A GAS FILTER ELEMENT The invention relates to a gas filter element formed by two juxtaposed layers, which is particularly suited to removing particles entrained in a gas stream. It is often necessary to purify air in a room or other enclosed space, which is loaded with suspended particles, such as removing paint dust from air in a paint spray booth. Methods and apparatus for cleaning gases for recycling or discharge is an area where a large amount of research has been undertaken and for this purpose numerous filters have been provided. However, these filters are prone to fast clogging of the filter elements. GB 917669 teaches a gas filter which comprised two layers of material which are each folded in a zig-zag manner. At alternate turning points of the zig-zags of each layer, the two layers are joined. As one layer is of greater area than the other layer, chambers are formed between the layers. Openings are provided through each of the layers so that gas passing through the filter is provided with a distorted flow and suspended particles removed. The present invention seeks to provide a filter element that is cheaper to manufacture and improves upon the filtration properties of the known filters. According to the present invention, there is provided a gas filter element formed by two juxtaposed layers, each layer comprising a plurality of zones, each defined by a first pair of fold lines, each zone including openings and intermediate fold lines substantially parallel with the said first pair, wherein the two layers are each deformed along said fold lines and joined together along contiguous fold lines thereby forming chambers between the layers, characterized in that the two layers are substantially identical in shape and size. The filter element provided by the present invention is far simpler to manufacture, since it is necessary to manufacture only one design of layer. The filter element is subject to low degrees of clogging of the element. Also, this filter element provides a high degree of filtration. Preferably, the cross-section through the chambers is substantially a parallelogram. In cases where very high degrees of filtration are required, further layers of material may be attached to the filter to act as further filter elements. Normally, the layers comprise a substantially rigid material. In one embodiment of the invention the material is paper, treated or untreated. Alternatively, the material may be a plastics material. The invention will now be described with reference to the accompanying drawings, in which: Fig. 1 shows cross-section through a folded layer of a first embodiment of the filter element according to the invention; Fig. 2 shows a view along the line A-A of Fig. 1 ; Fig. 3 shows a front view of a layer from B in Fig. 1 ; and Fig. 4 shows part of a filter element according to the first embodiment of the invention. Figures 1 to 3 show a layer 15 of rigid material. The layer 15 is divided into zones by pairs of parallel fold lines 1 and 2. Each zone is sub¬ divided into two pairs of wall elements 10 and 11 by parallel fold lines 1 , 2, 3. Each of the wall elements 10 extends between a fold line 2 and a fold line 3. Each of the wall elements 1 1 extends between a fold line 1 and a fold line 3. Each wall element 11 contains a plurality of openings 4. The layer 15 is folded in a zig-zag manner about each fold line 1 and 2, forming a concertina-shaped layer 15. The layer is also folded about fold lines 3. To form the filter element, as shown in Fig. 4, two substantially identical layers 15 are joined together along each fold line 2 to the opposite fold line 1. The folding of the two layers 15 is in opposite directions with regard to the . axis. This forms chambers 5 bounded by a wall element 10 and a wall element 11 of each of the two layers 15. In use, the unpurified air stream enters a chamber 5 of the filter element through the openings 4 of one layer 15. Subsequently, the air stream is deflected by wall elements 10, 11 . The air stream exits, substantially purified, through the openings 4 of the other layer 15. As will be appreciated, different designs of the filter element of this invention can be easily envisaged having more or less individual wall elements defining a chamber. It is essential that a high degree of symmetry be maintained so that the manufacturing process is kept cost efficient. It should be noted that throughout this specification, the word "fold" means a deformation, and the term "fold line" means a line about which a material is deformed. In alternative manufacturing processes, such as when the filter is made from plastics material, each element may be extruded or moulded. The fold lines would then relate to an area about which the element is deformed. It must also be noted that throughout this specification, the word "openings" means "perforations".

Claims: CLAIMS 1. A gas filter element formed by at least two juxtaposed layers, each of said two layers comprising a plurality of zones, each defined by a first pair of fold lines, each zone including openings and intermediate fold lines substantially parallel with the said first pair, wherein the two layers are each deformed along said fold lines and joined together along contiguous fold lines thereby forming chambers between the layers, characterized in that the two layers are substantially identical in shape and size. 2. A gas filter element according to claim 1 , wherein the openings are between two intermediate fold lines. 3. A gas filter element according to claim 1 or claim 2, wherein the cross-section through the chambers is substantially a parallelogram. 4. A gas filter element according to anyone of the preceding claims, wherein the layers are made of a substantially rigid material. 5. A gas filter element according to claim 4, wherein the rigid material is treated or untreated paper or a plastics material. 6. A gas filter element according to anyone of the preceding claims, wherein at least one additional layer is attached to said two layers so as to provide at least one further filter element.

Inventors: ANDREAE ERHARD CHARLES, ANDREAE, ERHARD, CHARLES
Applicants: ANDREAE ERHARD CHARLES, ANDREAE, ERHARD, CHARLES
Application year: 1994
Main classification: B01D45
IPC codes: B01D45